The present invention relates to a semiconductor device and its manufacturing technique and more particularly to a technique which is useful for the semiconductor device having a nonvolatile memory.
Some semiconductor devices include a nonvolatile memory circuit portion therein for storing a comparatively small amount of information, such as information used at the time of, for example, trimming, recovering, and LCD (Liquid Crystal Device) image adjustment, and the production number of a semiconductor device.
For example, Japanese Unexamined Patent Publication No. 2007-110073 (Patent Document 1) describes a semiconductor device having a nonvolatile memory circuit portion of this kind. In Patent Document 1, a configuration is disclosed, in which data rewrite (write and erase) is carried out by means of an FN tunnel current over the entire channel surface in a capacity portion for data write and erase of a nonvolatile memory cell. In the nonvolatile memory cell in Patent Document 1, a single layer floating gate electrode is formed over the main surface of a semiconductor substrate via a gate insulating film. At each position of the plane of the floating gate electrode, the capacity portion, the capacity portion for write/erase, and a read portion are arranged. The floating gate electrode is covered with a silicon nitride film and a silicon oxide film deposited thereover. The silicon nitride film has a function as an etching stopper when forming a contact hole in the silicon oxide film.
For example, in International Publication WO2005/101519 pamphlet (Patent Document 2), a configuration is disclosed, in which a silicon oxide film is provided between the silicon nitride film and the floating gate electrode in the semiconductor device having a nonvolatile memory circuit portion with the same configuration as that in Patent Document 1.
For example, Japanese Unexamined Patent Publication No. 2002-16249 (Patent Document 3) discloses a technique for providing a silicon nitride film formed by the low-pressure CVD method as a film for suppressing hydrogen from diffusing outwardly in the upper layer side of a film containing hydrogen, which covers a MIS, in order to effectively supply hydrogen to a gate insulating film of a MIS type element.